Aspirating cartridge syringe with gas actuation



R. B. BLACK March 18, 1969 ASPIRATING CARTRIDGE SYRINGE WITH GASACTUATION Sheet Filed March 5, 1968 mt if N Sheet ATTORA'YS R. B. BLACKMarch 18, 1969 ASPIRATING CARTRIDGE SYRINGE WITH GAS ACTUATION FiledMarch 5, 1968 United States Patent O 14 Claims ABSTRACT F THE DISCLOSUREHypodermic syringe adapted to be vactuated by uid pressure power meansfor effecting the delivery of liquid material from the syringe throughthe needle, the syringe being adapted to receive a disposable cartridgecontaining the liquid to be injected and having a closure at one endadapted to be punctured by the hypodermic needle and having a freepiston at its other end, mechanism being provided for controllablydelivering the fluid pressure to the free piston. The iluid pressurepower means includes a source of expandable uid under pressure, Withmechanism for recycling or lrecompressing the pressure iiuid. Provisionis also made for aspirating action in advance of making an injectionunder the inuence of the fluid pressure power.

The present application is a continuation-in-part of my applicationsSer. No. 509,517 filed Nov. 24, 1965, and Ser. No. 559,703 filed Apr.28, 1966, both now abandoned.

This invention relates to hypodermic syringes for injectingpharmaceuticals or other liquids into tissues, veins, or arteries. Theinvention is concerned with several irnportant improvements including anovel arrangement for manual control of the syringe, a novel power meansfor ejecting the contents of the syringe to supplant the hand forcecustomarily employed for this purpose, and a novel arrangement providingfor aspiration by the syringe in advance of the injection. The inventionis of especial advantage in making possible the achievement of all ofthese improvements in a single instrument, as will further appear.

Although various features of the invention have wide applicability inthe fields of medicine and dentistry, one use in which the invention isespecially advantageous is for the administration of local anesthetic inconnection with dentistry.

It is recognized that the use of hypodermic syringes, notably in thefield of dentistry, presents a number of problems, some of which arepsychological and some physical. Indeed, in the field of dentistry,although the hand actuated syringe is almost universally used throughoutthe world, nevertheless such a syringe remains a symbol of fear and painto many patients. In many cases this results in over stimulation of theadrenals which in many instances has caused the patient to go intosyncope with the loss of consciousness even before being touched withthe syringe.

In addition to adverse psychological factors of the well-known handoperated syringe, the hand operated syringe also has certain definitephysical disadvantages. For example, the spread grasp of the handrequired for expelling the material being administered by the syringe isnot conducive to steady control of the instrument with respect to needleinsertion in the tissue. For this reason, many operators prefer toinitially employ the pen grasp during insertion in the tissue for moreprecise control, after which the operator must change the position ofhis hand to assume the spread grasp in order 3,433,223 Patented Mar. 18,1969 ICC to accomplish the injection. It is difcult to make thistransition from one grasp to the other without moving or twisting thesyringe. Such movements of the hand in changing from one grasp to theother produces unfavorable psychological reaction as well as physicaldiscomfort to the patient, and can, in fact, be quite painful if theinstrument. is not carefully controlled. Moreover, the spread grasp isconducive to unintentional squirting or dripping of the medicine oranesthetic prior to the time that the needle is actually introduced intothe tissue which is definitely undesirable because of the bitter anddisagreeable taste of anesthetic solutions.

A major object of the present invention is to eliminate the foregoingdisadvantages of the prior art manually oper-ated syringe. Thus, theinvention contemplates the provision of a syringe which does not evenresemble in general appearance the well-known hand actuated syringe,thereby eliminating much of the adverse psychological influences abovereferred to.

In addition, the instrument provided in accordance with the presentinvention incorporates power actuating means in place `of the handactuated plunger of the prior art syringes, thereby eliminating thenecessity for employment of the basically awkward spread grasp requiredwith prior syringes.

It is also an object of the present invention to provide a hypodermicsyringe which may conveniently be held in the pen grasp for bothinsertion of the needle into the tissue and the control of theinstrument during the injection, and for this purpose the instrument ofthe present invention preferably incorporates a control element locatedintermediate the ends of the instrument and operable by a finger of thehand (i.e., either by the thumb or by one of the other four digits ofthe hand) Without requiring shift of the hand from one position toanother.

A still further object of the invention is to provide a syringe in whichit is unnecessary to utilize an elongated plunger or piston rod totransmit the force applied by the hand of the doctor to the ejectingpiston in the cartridge. With existing designs plungers of this typeoften contact the ejecting piston unevenly, and therefore result in theapplication of greater force to one side of the ejecting piston than theother, causing the walls of the ejecting piston to vibrate during itstravel down the cartridge, resulting in what patients describe as ascrunchy sound. The present invention completely eliminates thisproblem.

In considering still another aspect of the invention it is pointed outthat while provision for aspirating is not required for all purposes,for many purposes it is preferred and for some purposes it is essentialto provide for aspiration through the hypodermic needle just prior toinjection. This enables the operator to determined whether the tip ofthe needle has been inserted into a vein or artery, which is desired oressential for some purposes but is undesirable -for other purposes, sothat in either case it is important for the operator to be able todetermined whether or not the needle has penertated a blood vessel.

Aspiration for the foregoing purposes is a well-known technique and inthe well-known manual aspirating syringes the manual plunger iscustomarily withdrawn slightly just after insertion of the needle intothe tissues so that if the needle has entered a blood vessel a smallamount or globule of blood will be aspirated through the needle into thesyringe. The wall of the springe is customarily made of transparentmaterial so that such a globule of blood may be observed.

The present invention not only provides the advantages already broughtout above but further makes possible achieving those advantages in asyringe which is also capable of aspiration prior to making aninjection.. Moreover, the invention provides a novel aspiratingarrangement in which it is not necessary to withdraw the manual plungerin order to elect aspiration. Indeed, in the instrument of the inventionaspiration is effected by motion of the operating element in the samedirection as used to effect the injection.

In accordance with the invention the aspiration arrangementautomatically assures that aspiration will precede the making of aninjection A still further object is to provide a finger control for ahypodermic syringe which not only provides for aspiration but also Iforstarting and stopping of the power means and thus of the flow of theinjection liquid in the syringe, as well as for precise control over therate of flow of the pharmaceutical into the tissue.

How the foregoing objects and advantages are obtained, together withothers which are explained later, will appear more fully from thefollowing description referring to the accompanying drawings in which:

FIGURE 1 is a longitudinal sectional view through one form of theinstrument according to the invention;

FIGURE 2 is an enlarged transverse sectional view as compared to FIGURE1 and taken as indicated by the section line 2-2 of FIGURE l;

FIGURE 3 is a sectional view through certain parts of the instrumentshown in FIGURES 1 and 2 assembled with a recycling device;

FIGURE 4 is a longitudinal sectional view through an instrumentrepresenting a modification of the instrument of FIGURES 1 through 3;

FIGURES 5 and 6 are similar sectional views of the instrument of FIGURE4 but showing certain control and operating parts in differentpositions; and

FIGURES 7 and 8 are transverse sectional views taken as indicated bysection lines 7 7 and 8-8 on FIG- URES 4 and 5, respectively.

In connection with two of the embodiments illustrated in the drawings itis mentioned that the embodiment of FIGURES 1 to 3 inclusive isespecially suited to types of injections which do not require initialaspiration, examples of such types being the administration of localanesthetics in dentistry, and various intramuscular injections forinstance, in the administration of insulin. The embodiment of FIGURES 4to 8 provides the advantages of the embodiment of FIGURES 1 to 3 but inaddition the embodiment of FIGURES 4 to 8 further provides foraspiration in a novel manner as fully explained hereinafter. Thus theembodiment of FIGURES 4 to 8 may Ibe used not only for injections of thetypes mentioned just above, if aspiration is preferred, but in additionthe embodiment of FIGURES 4 to 8 may also be employed for many othertypes of injections Where aspiration is important or essential.

Turning now to the embodiment illustrated in FIG- URES 1 through 3inclusive, it is rst noted that the instrument is adapted to theemployment of cartridges of presently known type, namely a cartridgesuch as indicated at 61 having a free piston 62 in one end and having apuncturable diaphragm 55 at the other end. Such a cartridge permitsarresting the motion of the parts and thus for the making of multipleinjections from a given cartridge and controlling the rate of ow duringthe injection. The cartridge is received in the housing part 78 havingat its left end the ferrule 79 for cooperation with the mounting of aneedle 80, the inlet or inner end of which is adapted to penetrate thediaphragm 55 of the cartridge.

The righthand portion of the elongated housing, as indicated at 81, isadapted to receive the elongated piston v82 having a sealing ring 83near its righthand end, and the lefthand end of which is adapted to abutthe free piston 62 of the cartridge when the parts are assembled by thebayonet connection 84. The righthand end of the housing part 81 is openand threaded to cooperate with the cap member 85 containing a chamber 86for receiving a propellent material or actuating pressure fluid. Thischarge may be replenished if desired through a punctura'ble diaphragmsuch as indicated at S7.

In a typical case, this actuating fluid may comprise one of thewell-known synthetic fluorocarbons having a low boiling point, forinstance monochlorodiuoromethane, a source of which is known to thetrade as Freon 22 marketed by E. I. du Pont de Nemours & Co. Thismaterial introduced initially in liquid form will establish an internalpressure of approximately 135 p.s.i. at 76 F.

The cap has a central bore extended from the chamber 86 to the righthandend of the cylinder within the housing part 81 so as to communicate thepressure in the chamber 86 to the righthand end of the elongated piston82 and thereby drive that piston to the left against the free piston 62thus effecting discharge of the material to be injected.

As seen in FIGURES l and 2 the central portion of the piston, betweenthe lines indicated at 88 and 89 in FIGURE 1 is diametrically slotted,the slot being of tapered form as appears in FIGURE 2, in order toreceive the tapered or wedge element 90 which is normally urged intowedging engagement in the slot in the piston 82 =by means of thecompression spring 91 which may be adjusted by the screw 92. The wedgeelement 90 may be released by means of a finger button 93. Thisarrangement provides for arresting the motion of the parts and thus forthe making of multiple injections from a given cartridge and controllingthe rate of oW during the injection.

In connection with the embodiment of FIGURES 1 to 3 it is to -be notedthat the invention contemplates a recycling system in connection withthe power section of the syringe, namely the section incorporating thehousing part 81, the elongated piston 82 and the cap 85 with thepropellent charge therein. FIGURE 3 illustrates a preferred techniqueand equipment to be employed in connection with the recycling of thepower section of this instrument. Thus it will be seen that the powersection is positioned at the right in FIGURE 3 with the bayonetconnection parts 84 associated with a tube or sleeve 94, as indicated at84a. This sleeve 94 constitutes an extension from the cylinder 95 havinga piston 96 therein with a piston rod or stem 97 projecting into thesleeve 94 to the position where it may abut the lefthand end of theelongated piston 82 of the power section of the instrument.

At the lefthand end of the cylinder 95 a cap 98 is provided, having anair pressure or other uid pressure supply line 99 associated therewithfor introduction of pressure uid into the cylinder `95 back of thepiston 96. An accumulator chamber 100 is also desirably connected withthe righthand end of the cylinder 95 as by means of the pipe 101.

By the apparatus just described, after the piston 82 has been moved tothe left when viewed as in FIGURE 1 so as to drive the free piston 62into the cartridge, and when it is desired to recycle the syringe, thepower Section is separated from the cartridge section of the iustrumentand the power section is then placed into cooperative relation with therecycling mechanism as shown in FIGURE 3, whereupon by the introductionof pressure from the supply line 99 into the cylinder 95 the elongatedpiston of the power section of the syringe may -be driven back into thehousing part 81, thereby recycling the Freon 22 (E. I. du Pont deNemours & Co.) or other propellant from vapor to liquid phase in thechamber v86 and thus preparing the instrument for reuse. In this way agiven charge of the Freon or other propellant may readily be reused manytimes.

The instrument of FIGURES 1 through 3 inclusive is capable of employmentin situations where a multiplicity of injections are to be made from agiven charge. It is to be noted, however, if desired, the various partsmay be proportioned to accept cartridges designed for single injectionsrather than multiple injections. In all Cases various parts of theequipment are also readily capable of sterilization lfor reuse.

In FIGURES 4 through 8 another embodiment is illustrated, the instrumenthere shown being in many respects similar to that shown in FIGURES 1through 3. As in FIGURES 1 through 3, the instrument of FIG- URES 4through 8 is one in which the pressure fluid may be recycled, forinstance by a recycling mechanism of the kind illustrated in FIGURE 3.

The instrument of FIGURES 4 through 8 also incorporates another featureof importance, namely a system providing for aspiration prior to themaking of an injection.

As seen particularly in FIGURES 4 and 5, the instrument includes tubularmembers 102 and 103, having a bayonet connection 104 therebetween. Themember 102 has a cylindrical chamber therein adapted to receive acartridge comprising a cylinder 105 having a free piston 106 in one endand having a puncturable diaphragm 107 at the opposite end.

The left end of the member 102 is provided with a threaded cap member108 adapted to receive a cup 109, the cup being shiftable within themember 108 and being normally urged toward the right as viewed inFIGURES 4 and 5 by means of a coil spring 110, the range of movement ofthe cup being shown by comparison of FIGURES 4 and 5.

The tubular member 103 of the lassembly is adapted to receive the piston111 having a sealing ring 112 toward its righthand end and having at itslefthand end a harpoon 113 designed to penetrate the free piston 106.With this in mind the free piston 106 is advantageously formed ofrubber, so that the material will give as the harpoon enters thematerial,

At the righthand end of the tubular mem-ber 103 a cap 114 is provided,this cap being adapted to contain a charge of pressure fluid of the typehereinabove mentioned. A plug 115, formed of material which may bepenetrated by a charging needle is provided at the extremity of the cap114, so that when needed, additional pressure fluid may be introducedinto the pressure chamber.

When the pressure chamber is charged, the pressure thereof will actagainst the righthand end of the piston 111, thereby urging the piston111 to the left, as in the embodiment of FIGURES 1 through 3 describedabove. The motion of the piston 111 is adapted to be controlled by abrake 116 (see also FIGURE 7) of semicylindrical shape positoned on theunderside of the piston 111 and mounted in a 'bore provided in acylindrical part 117 formed at the lower side of the tubular member 103.This brake shoe 116 is urged upwardly against the lower surface of thepiston 111 by means of compression spring 118 which reacts against anadjustable screw plug 119.

The brake shoe 116 is controlled by a brake rod 120 which extendsupwardly th-rough an axial slot formed in the piston 111, the upper orfree end of the brake rod 120 being exposed outside of the tubularmember 103 in position to be contacted by the operating element or lever121. When the lever 121 is pressed downwardly, for instance asillustrated in FIGURE 6, the `brake rod 120 is depressed, therebydisplacing the brake shoe 116 from the lower surface of the piston 111,and thus releasing the piston for movement toward the left when viewedas in FIGURES 4 through 6, under the influence of the pressure fluidbehind the piston.

Lever 121 is mounted by means of a pivot 122 the ends of which aresupported in apertured lugs 12S-123 projecting from the tubular member103.

Lever 121 is further provided with an actuating finger 124 which is-received in a socket formed at the upper side of a push rod 125 whichis mounted for reciprocation or shifting movement lengthwise of theinstrument within a groove or slot formed in the inner surface of thetubular member 103. Preferably the push rod 125 and the slot in which itWorks are so shaped as to restrain outward dislodgement of the push rod,while permitting its longitudinal motion.

The push rod 125 is positioned so that its left-hand end will engage therighthand end of the cylinder of the cartridge inserted into the tubularmember 102. The purpose of this arrangement will be described shortlybelow.

Attention is now called to the lefthand end of FIG- URE 5 where there isshown a hypodermic needle 126 mounted by means of acap 127, with theinner end of the needle 126 penetrating the diaphragm 107 at the leftend of the cartridge. Attention is also called to the fact that thetubular member 102 is provided with an elongated aperture 128 in asidewall thereof through which the cartridge is visible. With thecylinder 105 of the cartridge formed of transparent material, as iscustomary, the aperture 128 in the tubular member 102 serves, in effect,as a window through which the interior of the cartridge may be observed.

The purpose and operation of various parts of the device as describedabove and illustrated in FIGURES 4 through 8, is as follows:

First, with the two tubular members 102 and 103 of the instrumentseparated (by disconnection of the bayonet joint 104) and in the absenceof the hypodermic needle 126, an anesthetic cartridge is inserted intothe tubular member 102 in the position indicated in FIGURE 4. The twotubular parts of the assembly are then brought together, and the bayonetjoint 104 appropriately fastened. During this assembly, the harpoon 113penetrates the free piston 106, at which time the assembly of partsappears as shown in FIGURE 4.

The hypodermic needle 126 is then inserted and fastened in place bymeans of the screw cap 127, and during this insertion the inner end ofthe needle penetrates the diaphragm 107, and the instrument is now-ready for use. When the two parts of the casing are assembled it willbe seen that the pressure uid in the capsule 114 reacts between the freepiston and the cartridge on the one hand and the part 103 of the casingon the other hand, and further that the piston 111 is operativelyinterposed between the free piston and the charge of the pressure fluid.

When used, the needle is of course inserted in the target area of thetissue, and in doing this, the instrument may be handled in the mannerdescribed above, namely by employg the pen grasp. The operating elementor lever 121 may then be actuated, for instance by the thumb, or withinthe grasp of the hand, without requiring shift in position of the hand.The initial motion of the lever 121, for instance the motion from theposition shown in FIG- URE 4 to the position shown in FIGURE 5 willshift the push rod 125 to the left and thereby shift the cylinder 105 ofthe cartridge to the left, for instance from the position shown inFIGURE 4 to the position shown in FIGURE 5, the spring being compressedduring this action. Moreover, at this time, because of the penetrationof the harpoon 113 in the rubber of the free piston 106, the free pistonis retained in its initial position. The action just described resultsin reduction of pressure within the cartridge and, in consequence anaspiration effect through the needle 126 into the left end of thecartridge. In the event that the needle has been positioned in a bloodvessel, for instance in a vein, this aspirating effect will draw intothe cartridge a small globule of blood, for instance as indicated at Bin FIGURE 5. This globule is visible through the transparent cylinder105 and through the window 128 in the tubular member 102, and thereby,the operator is apprised of the positioning of the needle within a bloodvessel.

As `above mentioned, an instrument of this kind may be employed forvarious different purposes, for some of which it is desired that theneedle be positioned within a blood vessel and for others of which it isnot desired that the needle be positioned within a blood vessel. In theformer case, the aspiration of the globule of blood will at once advisethe operator that the needle is properly positioned to proceed with theinjection. In the latter case, the aspiration of the globule of bloodwill advise the operator that the needle is not porperly positioned,`and the operator may then release the lever 121 and thereafterreposition the needle so as to locate it in the tissue exteriorly of theblood vessels.

In the event of either type of use, after the operator has determinedthat the needle is positioned as intended, the operator may then furtherdepress the lever 121, in consequence of which the brake rod 120 isengaged and displaced, thus reelasing the braking action of the brakeshoe 116 against the piston 111, so that the piston will be moved underthe inuence of the tluid pressure behind it, thereby advancing the freepiston 106 into the cylinder 105 of the cartridge and thus injecting thecharge of the cartridge through the needle into the target area.

This control arrangement provides for selective incremental expansion`of the pressure fluid and thus for controlled injection of the materialin the cartridge so that if desired multiple injections may be made`from a single cartridge.

ltdesired the operator may use the instrument of FIGURES 4 through y8 inthe making of several injections, the quantity of material injectedbeing readily controlled by release and re-engagement of the brake shoe116. A spent cartridge may readily be removed by separation of the twotubular parts of the instrument 102 and 103, thereby permitting removalof the spent cartridge from the open end of the tubular member 102. Thetree piston 106 of a spent cartridge may also be readily removed fromthe harpoon 113. The pressure uid in the instrument may then be recycledin the manner described above with reference to FIGURE 3. To avoidstriking the tip of the harpoon 113 during recycling, the end of thepiston rod 97 (see FIGURE 3) may be provided with a recess or boreaccommodating the harpoon 113, so that the recycling pressure will thenbe transmitted directly from the end of the piston rod 97 to the end ofthe piston 111 of the instrument.

In the instrument of FIGURES 4 through 8 inclusive, it is thus possibleto etect aspiration in advance of the injection. Indeed this instrumentassures that aspiration will be effected in advance of injection. Inthis connection it will be observed that the operating element or lever121 has a normal sense or direction of motion which automaticallyprovides sequentially for aspiration and then for injection.

fIt is to be noted in connection 'with both embodiments of theinstrument that provision is made for operation or control with theinstrument held in the hand by the pen type grip. Thus the control maybe operated by pressing on the control element with the thumb or one ormore of the other tingers. In both embodiments illustrated and describedthe control element is positioned in general in a region intermediatethe ends of the elongated instrument, thereby providing readyaccessibility by a nger or ngers of the hand in which the instrument isheld. And in all cases, no change in position of the instrument isneeded for insertion of the needle and for subsequent actuation todeliver the injection, nor is any change in position of the hand evenneeded to effect aspiration with embodiment of FIGURES 4 through 8.

Both embodiments of the syringe as disclosed are also of specialadvantage in being capable of employment of cartridges of a type nowwidely available.

Cartridges available in a variety of types and containing a variety ofmaterials may be used, many of such` cartridges having either a glass orplastic case, with a well-known type of rubber diaphragm for needlepuncturing, and havin-g a free piston at the opposite end.

For use as a propellant, certain Freon gases other than that mentionedmay be used, as may also certain Genetrons (General Chemical Div.) andUcons (Carbide and Carbon Chemicals Co.). Another specific example of anappropriate material is dichlorodifluoromethane which is available underthe trade name Freon l2 (E. I. du Pont de Nemours & Co.).

Various of these uorocarbons are colorless, almost odorless,nonllammable and virtually non-toxic so they are highly suitable to Iusein the medical eld without hazard.

I claim: Y

1. A hypodermic syringe comprising a tubular body for receiving a pistonand cylinder type cartridge having a transparent cylinder Wall andcontaining material to be injected, the tubular body having a windowproviding for observation of a cartridge received in the tubular bodyand the tubular body havin-g means for mounting a hypodermic needle inposition to penetrate the cartridge, means for advancing the cylinder ofa cartridge received in the tubular body and for concurrentlyrestraining the piston as against advancement to thereby provide forreduction of pressure in the cartridge and thus effect aspirationthrough the needle, and means for advancing the piston into the cylinderand thus elect expulsion of the material to be injected from thecartridge through the needle.

2. A construction according to claim 1 in 'which the means for advancingthe piston includes a source of pressure iiuid and means forcontrollably applying the pressure of the uid to the piston to effectadvancement thereof in the cylinder.

3. A construction according to claim 1 and further including a commonoperating element for the means for advancing the cylinder and thelmeans for advancing the piston.

4. A construction according to claim 3` in which the operating elementis mounted for movement in one direction for operating the syringe, theconstruction further including means providing for sequentialadvancement of the cylinder and then of the piston by movement of theoperating element in said one direction.

5. A hypodermic syringe having a chamber for receiving a disposablecartridge having a closure at one end adapted to be penetrated by ahypodermic needle and having a free piston at its other end, thecartridge further havin-g a transparent cylinder enclosing the materialto be injected, the syringe chamber providing for visual observation ofthe cartridge received therein and having means for mounting ahypodermic needle in position to penetrate said cartridge closure,mechanism connected with the free piston and providing alternatively forrelative advancement and withdrawal of the piston with respect to thecylinder of the cartridge received in the syringe chamber, an operatingelement for the syringe mounted for movement in one direction foroperating the syringe, and means providing for sequential relativewithdrawal and then advancement of the piston with respect to thecylinder by movement of the operating element in said one direction.

6. A hypodermic syringe comprising an elongated housing with means formounting a hypodermic needle at one end thereof, the housing forming achamber for receiving a disposable injection liquid cartridge having atone end a closure adapted to be penetrated by a needle mounted on thehousing and having a free piston at its other end, uid pressure powermeans separate from the cartridge but adapted to act on the free pistonto deliver said liquid from the cartridge through the needle, the powermeans including a source of expandable pressure Huid in the housing ofthe syringe between the cartridge and the end of the housing remote fromthe needle, and control means providing for selective incrementalexpansion of the pressure uid and thus for regulation of the delivery ofsaid liquid from the cartridge under the action of said power means.

7. A syringe according to claim 6 in which the power means includes apiston device operatively interposed between the free piston of thecartridge and the pressure fluid of said source and in which the controlmeans comprises a manually releasable brake for controllably restrainingmotion of the piston device.

8. A syringe according to claim 6 and further including means forcontrollably retracting the free piston of the cartridge to electaspiration.

9. A hypodermic syringe comprising an elongated housing having a chamberfor receiving a disposable injection liquid cartridge having at one enda closure adapted to be penetrated by a hypodermic needle and having aee piston at the other end, the housing being formed of two separableand interengageable parts, a rst part of the housing having means yformounting a hypodermic needle at the end thereof remote from the otherpart in a position to penerate said closure, fluid pressure power meansfor advancing the free piston ofthe cartridge, the power means beingmounted in the second part of the housing to be separable with saidsecond part when it is separated from the i'lrst part of the housing,the power means including a source of expandable pressure uid, andmanual control means mounted on said second part of the housing andproviding for selective `incremental expansion of the pressure iluid andthus for regulation of the delivery of said liquid from the cartridgeunder the action of said power means.

10. A syringe according to claim 9 in which the power means furtherincludes a Ipiston device operatively interposed between the free pistonofthe cartridge and the pressure lluid of said source when the two partsof the housing are interengaged, when the two parts of the housing areseparated said piston device being accesible to provide forrecompression of the pressure fluid of said source by applying force tothe piston device.

11. A syringe according to claim 9 in which the power means furtherincludes a piston device operatively inter posed between the free pistonof the cartridge and the pressure uid of said source When the two partsof the housing are interengaged, and the control means cornprises amanually releasable brake for controllably restraining motion of thepiston device.

12. A hypodermic syringe comprising an elongated housing formed of firstand second separable and interengageable parts, the first part having achamber for receiving a disposable injection liquid cartridge having atone end a closure adapted to be penetrated by a hypodermic needle andhaving a free piston at the other end and the rst part of the housingfurther including means for mounting a hypodermic needle at the endthereof remote from the second part in a position to penetrate saidclosure, tluid pressure power means for advancing the free piston of thecartridge including a charge of expandable pressure uid behind the freepiston arranged to react between the -free piston and the second part ofthe housing when the two parts of the housing are interengaged, andmanual control means providing for selective incremental delivery ofsaid liquid from the cartridge under the influence of the pressurefluid.

13. A hypodermic syringe according to claim 12 in which the power meansfor advancing the free piston includes a power piston operativelyinterposed between the free piston and the charge of pressure fiuid andfurther in which the manual control means includes a releasable brakefor the reciprocation `of the power piston, the brake being biased tobrake-applied position, and the power piston being accessible when thetwo parts of the casing are separated and being movable to recycle thepressure fluid.

14. A hypodermic syringe comprising an elongated housing having an openend; a cartridge iitting within the housing and containing the materialto be injected; a hypodermic needle at the end ofthe housing oppositesaid open end; a free piston in the cartridge forming a chamber for thematerial to be injected; a hollow closure member adapted to be removablysecured to said open end of the housing; a power piston in said closuremember; a propellent compartment; means for establishing communicationbetween the propellent `compartment and the rear face of the powerpiston; and brake mechanism for controlling the movement of said powerpiston under the influence of said propellant, said power piston beingadapted to move the free piston to discharge the material to beinjected.

References Cited UNITED STATES PATENTS 2,168,437 8/1939 Buerckln 12S-2182,699,167 l/1955 Raiche 12S-216 3,306,290 2/1967 Weltman 12S-2183,334,788 8/1967 Hamilton 12S-218 RICHARD A. GAUDET, Primary Examiner.

MARTIN F. MAJESTIC, Assistant Examiner.

